The purpose of this study is to develop, characterize and employ monoclonal antibodies against Epstein-Barr virus (EBV)-determined proteins, notably the nuclear antigen (EBNA), which could not be prepared to date by standard immunization-fusion techniques. The reagents will be applied to the molecular analysis of EBV-cycle and tested in clinical diagnosis. Possible therapeutic use of the monoclonals in the future will be considered. The approach we propose is based on our recent development, EBV receptor-implantation onto receptor negative cells. This permits broadening of the EBV-host cell range beyond primate B lymphocytes. We have shown recently that infection of mouse lymphocytes by EBV results in the synthesis of EBV-determined nuclear (EBNA), and early (EA), and virus capsid (VCA) antigens. Thus, mice can now be immunized with syngeneic cells in which sthe only immunogenic proteins are products of EBV-life cycle, significantly increasing chances to obtain monoclonal anti-EBNA, EA and VCA antibodies. The monoclonals will be produced by the hybridoma technique, after repetitive immunization of Balb/c mice with EBV-infected syngeneic lymphocytes. The antibodies will be purified, characterized, and tested for their activity and specificity in comparison to the normal Burkitt's lymphoma and nasopharyngeal carcinoma-derived human sera. At the clinical level, anti-EBNA antibody of high titer will likely increase the accuracy of diagnosis with respect to EBV involvement in lymphoproliferative diseases resulting from acquired (i.e., AIDS) or inherited (i.e., XLP) immunodeficiency, lymphomas and carcinomas. Direct immunofluorescence and radiommunoassay for EBNA detection will be developed. Increased sensitivity of EBNA detection may allow reevaluation of the stored tissues from various malignancies in which EBV was suspected to play an etiologic role. In basic research, the monospecific reagents will be applied to the isolation, biochemical and functional characterization of proteins associated with the isolation, biochemical and functional characterization of proteins associated with the life cycle of EBV. In particular, identification of EBNA may facilitate characterizing the cell-transforming function of EBV responsible for the life-threatening biological activity of the virus. This will be achieved through the use of immunoabsorbent columns, immunoprecipitation and other techniques based on the specific antibody-antigen interactions.